What if Firefox loses your tabs ?

It happened to me today, not sure if it was because I closed my main window and firefox had some other window in the back ? But the next run all my tabs were gone, and they were nowhere to be found in my 'Recently Closed Tabs' list. My sessionstore.js was huge, but re-opening Firefox only brought up the default homepage.

If this happens to you on re-opening Firefox, don't blink a second, make a copy of your sessionstore.bak and sessionstore.js so that Firefox doesn't replace them and you lose everything.